1. Field of the Invention
The present invention relates to an apparatus for sharpening a cutting edge on a blade which has dulled. From time to time it becomes necessary to straighten, realign and sharpen the microscopic edge of a cutting tool such as a knife. It is important to maintain a uniform pressure and a proper even edge angle when sharpening a cutting edge. Previous sharpening devices have involved complex implements which commonly remove material from the cutting edge. Additionally, many of the previous devices are designed for use either by a right handed or left handed person while sharpening one side of the edge at a time, not both. The present invention relates to a sharpener having a substantially enclosed biasing assembly that resists contamination during use and provides for improved cleaning.
2. Description of the Prior Art
Devices for sharpening blades and the like fall into three broad categories:
(a) devices having sharpening elements in permanent fixed relationship such as that disclosed in U.S. Pat. Nos. 578,440; 1,851,520; 1,909,743; 2,767,530 and 5,163,251; PA0 (b) devices having sharpening elements in movable relationship to each other with fully exposed biasing assemblies such as that disclosed in U.S. Pat. No. 4,934,110; and PA0 (c) devices having sharpening elements in movable relationship to each other with biasing assemblies not shielded from debris such as that disclosed in U.S. Pat. Nos. 1,041,631; 1,570,083; 2,124,646; 2,885,836; 4,550,632; and 4,624,079 as well as Patent Nos. GB 293,785 and GB 517,242.
There are problems and limitations with all of these devices. Devices having sharpening elements in fixed relationship to each other are relatively inefficient, needing considerably more resistance when passing a blade between the elements in order to sharpen the blade and may not provide optimal sharpening of the blade. These arrangements often remove perceptible metal fragments from the blade which shortens the useful blade life and is undesirable for contamination reasons.
In movable element arrangements exposed biasing means such as counterweights, lever arms, springs and the like, are prone to collect food particulates and other debris during use. These sharpening devices are often used in food processing plants where the blades to be sharpened are full of meat particles. Where the spring is not shielded from debris that may accumulate during use, this condition can cause related problems of contamination and disease.
In certain food industries, governmental authorities regulate and inspect the processing of food for sale to consumers. While many sharpening devices provide a sharp knife, these known devices have disadvantages of exposed parts or configurations that collect debris and contribute to the problems of contamination and disease. Additionally, cleaning the exposed parts of known devices is costly as these require specific attention to the meshed windings of springs and counterweights and the like. Cleaning may require disassembly of the housing in order to clean the apparatus and remove the debris. Sometimes when an operator is using prior art devices the operator may be of the misconception, in not seeing the debris that is collecting, that all is well and the apparatus does not need cleaning, which in fact is not the case. Thus, there is a need for a blade sharpening apparatus of the present invention that eliminates operator error due to unseen contamination, reduces cleaning and maintenance costs, and eliminates contamination thereof.